1. Field of the Invention
This invention pertains to fluid pumping apparatus. Particularly, this invention pertains to peristaltic pumps in which a fluid is passed through a flexible tubing by moving occlusions of the tubing.
2. Description of the Prior Art
Peristaltic or tube pumps are used where it is desirable avoid pump contamination by the pumped fluid or contamination of the fluid pumped. They are used for pumping corrosive materials, in laboratories and in medical fields. No fluid contamination occurs since pumped fluid only contacts the insides of the tubing walls. The chemical resistance of the tubing, thus determines the limits of the resistance to contamination.
Rollers are typically used to cause a deformation or occlusion of the tubing which rollers are advanced both to drive the fluid in the tubing forward, while creating a rearward vacuum suction behind the portion of the fluid being pushed forward. Each roller is typically a cylinder. The axis of the cylindrical roller is disposed transversely to the tubing. As the roller bears on the tubing, it exerts forces on the central portion of the tubing, but also causes a flattening of the edges. Ultimately, the tubing must be advanced through the pump to subject a fresh tubing segment to the rollers, or replaced as a result of the frictional forces on the tubing and repeated tubing deformation. Often this is not of significant concern when the pumping is used on an intermittant or occasional basis. However, where the pumping apparatus is fixed in a unit of machinery, it is often desirable to minimize pump maintenance.